Treatment with indinavir, zidovudine, and lamivudine in adults with human immunodeficiency virus infection and prior antiretroviral therapy

HIV cell-to-cell transmission: effects on pathogenesis and antiretroviral therapy

HIV spreads more efficiently in vitro when infected cells directly contact uninfected cells to form virological synapses. A hallmark of virological synapses is that viruses can be transmitted at a higher multiplicity of infection (MOI) that, in vitro, results in a higher number of proviruses. Whether HIV also spreads by cell-cell contact in vivo is a matter of debate. Here we discuss recent data that suggest that contact-mediated transmission largely manifests itself in vivo as CD4+ T cell depletion. The assault of a cell by a large number of incoming particles is likely to be efficiently sensed by the innate cellular surveillance to trigger cell death. The large number of particles transferred across virological synapses has also been implicated in reduced efficacy of antiretroviral therapies. Thus, antiretroviral therapies must remain effective against the high MOI observed during cell-to-cell transmission to inhibit both viral replication and the pathogenesis associated with HIV infection.

Inhibition of HIV-1 entry by the tricyclic coumarin GUT-70 through the modification of membrane fluidity

Membrane fusion between host cells and HIV-1 is the initial step in HIV-1 infection, and plasma membrane fluidity strongly influences infectivity. In the present study, we demonstrated that GUT-70, a natural product derived from Calophyllum brasiliense, stabilized plasma membrane fluidity, inhibited HIV-1 entry, and down-regulated the expression of CD4, CCR5, and CXCR4. Since GUT-70 also had an inhibitory effect on viral replication through the inhibition of NF-κB, it is expected to be used as a dual functional and viral mutation resistant reagent. Thus, these unique properties of GUT-70 enable the development of novel therapeutic agents against HIV-1 infection.

Non-proteolytic functions of microbial proteases increase pathological complexity

Proteases are enzymes that catalyse hydrolysis of peptide bonds thereby controlling the shape, size, function, composition, turnover and degradation of other proteins. In microbes, proteases are often identified as important virulence factors and as such have been targets for novel drug design. It is emerging that some proteases possess additional non‐proteolytic functions that play important roles in host epithelia adhesion, tissue invasion and in modulating immune responses. These additional “moonlighting” functions have the potential to obfuscate data interpretation and have implications for therapeutic design. Moonlighting enzymes comprise a subcategory of multifunctional proteins that possess at least two distinct biological functions on a single polypeptide chain. Presently, identifying moonlighting proteins relies heavily on serendipitous empirical data with clues arising from proteins lacking signal peptides that are localised to the cell surface. Here, we describe examples of microbial proteases with additional non‐proteolytic functions, including streptococcal pyrogenic exotoxin B, PepO and C5a peptidases, mycoplasmal aminopeptidases, mycobacterial chaperones and viral papain‐like proteases. We explore how these non‐proteolytic functions contribute to host cell adhesion, modulate the coagulation pathway, assist in non‐covalent folding of proteins, participate in cell signalling, and increase substrate repertoire. We conclude by describing how proteomics has aided in moonlighting protein discovery, focusing attention on potential moonlighters in microbial exoproteomes.

Promoter Targeting RNAs: Unexpected Contributors to the Control of HIV-1 Transcription

In spite of prolonged and intensive treatment with combined antiretroviral therapy (cART), which efficiently suppresses plasma viremia, the integrated provirus of HIV-1 persists in resting memory CD4⁺ T cells as latent infection. Treatment with cART does not substantially reduce the burden of latent infection. Once cART is ceased, HIV-1 replication recrudesces from these reservoirs in the overwhelming majority of patients. There is increasing evidence supporting a role for noncoding RNAs (ncRNA), including microRNAs (miRNAs), antisense (as)RNAs, and short interfering (si)RNA in the regulation of HIV-1 transcription. This appears to be mediated by interaction with the HIV-1 promoter region. Viral miRNAs have the potential to act as positive or negative regulators of HIV transcription. Moreover, inhibition of virally encoded long-asRNA can induce positive transcriptional regulation, while antisense strands of siRNA targeting the NF-κB region suppress viral transcription. An in-depth understanding of the interaction between ncRNAs and the HIV-1 U3 promoter region may lead to new approaches for the control of HIV reservoirs. This review focuses on promoter associated ncRNAs, with particular emphasis on their role in determining whether HIV-1 establishes active or latent infection.

Epigenetic heterogeneity in HIV-1 latency establishment

Despite prolonged antiretroviral therapy, HIV-1 persists as transcriptionally inactive proviruses. The HIV-1 latency remains a principal obstacle in curing AIDS. It is important to understand mechanisms by which HIV-1 latency is established to make the latent reservoir smaller. We present a molecular characterization of distinct populations at an early phase of infection. We developed an original dual-color reporter virus to monitor LTR kinetics from establishment to maintenance stage. We found that there are two ways of latency establishment i.e., by immediate silencing and slow inactivation from active infection. Histone covalent modifications, particularly polycomb repressive complex 2 (PRC2)-mediated H3K27 trimethylation, appeared to dominate viral transcription at the early phase. PRC2 also contributes to time-dependent LTR dormancy in the chronic phase of the infection. Significant differences in sensitivity against several stimuli were observed between these two distinct populations. These results will expand our understanding of heterogeneous establishment of HIV-1 latency populations.

The triple threat of HIV-1 protease inhibitors

Newly released human immunodeficiency virus type 1 (HIV-1) particles obligatorily undergo a maturation process to become infectious. The HIV-1 protease (PR) initiates this step, catalyzing the cleavage of the Gag and Gag-Pro-Pol structural polyproteins. Proper organization of the mature virus core requires that cleavage of these polyprotein substrates proceeds in a highly regulated, specific series of events. The vital role the HIV-1 PR plays in the viral life cycle has made it an extremely attractive target for inhibition and has accordingly fostered the development of a number of highly potent substrate-analog inhibitors. Though the PR inhibitors (PIs) inhibit only the HIV-1 PR, their effects manifest at multiple different stages in the life cycle due to the critical importance of the PR in preparing the virus for these subsequent events. Effectively, PIs masquerade as entry inhibitors, reverse transcription inhibitors, and potentially even inhibitors of post-reverse transcription steps. In this chapter, we review the triple threat of PIs: the intermolecular cooperativity in the form of a cooperative dose-response for inhibition in which the apparent potency increases with increasing inhibition; the pleiotropic effects of HIV-1 PR inhibition on entry, reverse transcription, and post-reverse transcription steps; and their potency as transition state analogs that have the potential for further improvement that could lead to an inability of the virus to evolve resistance in the context of single drug therapy.

HIV therapy-the state of art

HIV Attachment. In this cross section, HIV is shown at the top and a target cell is shown at the bottom in blues. HIV envelope protein (A) has bound to the receptor CD4 (B) and then to coreceptor CCR5 (C), causing a change in conformation that inserts fusion peptides into the cellular membrane Antiretroviral therapy changed the face of HIV/AIDS from that of soon and certain death to that of a chronic disease in the years following introduction of highly active antiretroviral therapy in 1995-1996 (initially termed HAART, but now most often abbreviated to ART since not all combinations of regimens are equally active). Since then, many new agents have been developed and introduced in response to problems of resistance, toxicity, and tolerability, and great advances have been achieved in accessibility of HIV drugs in resource-poor global regions. Potential challenges that providers of HIV therapy will face in the coming decade include continuing problems with resistance, especially where access to drugs is inconsistent, determining how best to combine new and existing agents, defining the role of preventive treatment (pre-exposure prophylaxis or PrEP), and evaluating the potential of strategies for cure in some populations.

Potential implication of residual viremia in patients on effective antiretroviral therapy

The current antiretroviral therapy (ART) has suppressed viremia to below the limit of detection of clinical viral load assays; however, it cannot eliminate viremia completely in the body even after prolonged treatment. Plasma HIV-1 loads persist at extremely low levels below the clinical detection limit. This low-level viremia (termed "residual viremia") cannot be abolished in most patients, even after the addition of a new class of drug, i.e., viral integrase inhibitor, to the combined antiretroviral regimens. Neither the cellular source nor the clinical significance of this residual viremia in patients on ART remains fully clear at present. Since residual plasma viruses generally do not evolve with time in the presence of effective ART, one prediction is that these viruses are persistently released at low levels from one or more stable but yet unknown HIV-1 reservoirs in the body during therapy. This review attempts to emphasize the source of residual viremia as another important reservoir (namely, "active reservoir") distinct from the well-known latent HIV-1 reservoir in the body, and why its elimination should be a priority in the effort for HIV-1 eradication.

Lung cancer patients harboring epidermal growth factor receptor mutation among those infected by human immunodeficiency virus

With the advent of antiretroviral therapy, lung cancer has become a crucial health problem among individuals living with human immunodeficiency virus (HIV). In East Asian populations, the frequency of lung cancer patients harboring epidermal growth factor receptor (EGFR) mutations is greater than in other populations. Herein, we present two cases of advanced non-small cell lung cancer with EGFR mutations in patients treated with EGFR-tyrosine kinase inhibitors. Both patients were male, 67 and 59 years of age, with known HIV infection and immunologically stable disease with antiretroviral therapy. Case 1 was treated with erlotinib for recurrent adenocarcinoma metastasizing to the liver and brain harboring EGFR mutation in exon 21 L858R. The duration of treatment efficacy was 9.7 months. Case 2 had an EGFR mutation exon 19 in-frame deletion with bone metastasis and was treated with gefitinib for 22.1 months in combination with antiretroviral therapy. These advanced lung cancer patients living with HIV with EGFR mutations demonstrate the promising effectiveness and safety of EGFR-tyrosine kinase inhibitors concomitant with antiretroviral therapy for an extended period.

Estimating HIV-1 fitness characteristics from cross-sectional genotype data

Despite the success of highly active antiretroviral therapy (HAART) in the management of human immunodeficiency virus (HIV)-1 infection, virological failure due to drug resistance development remains a major challenge. Resistant mutants display reduced drug susceptibilities, but in the absence of drug, they generally have a lower fitness than the wild type, owing to a mutation-incurred cost. The interaction between these fitness costs and drug resistance dictates the appearance of mutants and influences viral suppression and therapeutic success. Assessing in vivo viral fitness is a challenging task and yet one that has significant clinical relevance. Here, we present a new computational modelling approach for estimating viral fitness that relies on common sparse cross-sectional clinical data by combining statistical approaches to learn drug-specific mutational pathways and resistance factors with viral dynamics models to represent the host-virus interaction and actions of drug mechanistically. We estimate in vivo fitness characteristics of mutant genotypes for two antiretroviral drugs, the reverse transcriptase inhibitor zidovudine (ZDV) and the protease inhibitor indinavir (IDV). Well-known features of HIV-1 fitness landscapes are recovered, both in the absence and presence of drugs. We quantify the complex interplay between fitness costs and resistance by computing selective advantages for different mutants. Our approach extends naturally to multiple drugs and we illustrate this by simulating a dual therapy with ZDV and IDV to assess therapy failure. The combined statistical and dynamical modelling approach may help in dissecting the effects of fitness costs and resistance with the ultimate aim of assisting the choice of salvage therapies after treatment failure.

Mutations conferring drug resistance represent major threats to the therapeutic success of highly active antiretroviral therapy (HAART) against human immunodeficiency virus (HIV)-1 infection. Viral mutants differ in their fitness and assessing viral fitness is a challenging task. In this article, we estimate drug-specific mutational pathways by learning from clinical data using statistical techniques and incorporate these into mathematical models of in vivo viral infection dynamics. This approach enables us to estimate mutant fitness characteristics. We illustrate our method by predicting fitness characteristics of mutant genotypes for two different antiretroviral therapies with the drugs zidovudine and indinavir. We recover several established features of mutant fitnesses and quantify fitness characteristics both in the absence and presence of drugs. Our model extends naturally to multiple drugs and we illustrate this by simulating a dual therapy with ZDV and IDV to assess therapy failure. Additionally, our modelling approach relies only on cross-sectional clinical data. We believe that such an approach is a highly valuable tool in assisting the choice of salvage therapies after treatment failure.

A mechanistic theory to explain the efficacy of antiretroviral therapy

In the early years of the AIDS epidemic, a diagnosis of HIV-1 infection was equivalent to a death sentence. The development of combination antiretroviral therapy (cART) in the 1990s to combat HIV-1 infection was one of the most impressive achievements of medical science. Today, patients who are treated early with cART can expect a near-normal lifespan. In this Opinion article, we propose a fundamental theory to explain the mechanistic basis of cART and why it works so well, including a model to assess and predict the efficacy of antiretroviral drugs alone or in combination.

Addiction to multiple oncogenes can be exploited to prevent the emergence of therapeutic resistance

Many cancers exhibit sensitivity to the inhibition of a single genetic lesion, a property that has been successfully exploited with oncogene-targeted therapeutics. However, inhibition of single oncogenes often fails to result in sustained tumor regression due to the emergence of therapy-resistant cells. Here, we report that MYC-driven lymphomas frequently acquire activating mutations in β-catenin, including a previously unreported mutation in a splice acceptor site. Tumors with these genetic lesions are highly dependent on β-catenin for their survival and the suppression of β-catenin resulted in marked apoptosis causally related to a decrease in Bcl-xL expression. Using a novel inducible inhibitor of β-catenin, we illustrate that, although MYC withdrawal or β-catenin inhibition alone results in initial tumor regression, most tumors ultimately recurred, mimicking the clinical response to single-agent targeted therapy. Importantly, the simultaneous combined inhibition of both MYC and β-catenin promoted more rapid tumor regression and successfully prevented tumor recurrence. Hence, we demonstrated that MYC-induced tumors are addicted to mutant β-catenin, and the combined inactivation of MYC and β-catenin induces sustained tumor regression. Our results provide a proof of principle that targeting multiple oncogene addicted pathways can prevent therapeutic resistance.

HIV DNA in CD14+ reservoirs is associated with regional brain atrophy in patients naive to combination antiretroviral therapy

OBJECTIVE

To examine associations between regional brain volumes and HIV DNA in peripheral CD14 cells (monocytes) among HIV-infected individuals naive to combination antiretroviral therapy (cART).

DESIGN

A prospective study of HIV-infected Thai individuals who met Thai national criteria for cART initiation. Enrolment was stratified by HIV DNA in a blinded fashion.

METHODS

CD14 cells were isolated from peripheral mononuclear cells to high purity (median 91.4% monocytes by flow cytometry), and HIV DNA was quantified by multiplex real-time PCR. Baseline regional brain volumes obtained by T1-weighted 1.5-Tesla MRI were compared between HIV DNA groups using analysis of covariance (ANCOVA).

RESULTS

We studied 60 individuals with mean (SD) age of 34.7 (7.0) years, CD4 T-lymphocyte count of 232 (137) cells/μl and log10 plasma HIV RNA of 4.8 (0.73). Median (interquartile range, IQR) HIV DNA copy number per 10 CD14 cells was 54 (102). Using our previously determined optimal cut-point of 45 copies/10 cells for this cohort, a threshold value above which CD14 HIV DNA identified HIV-associated neurocognitive disorders (HANDs), we found that CD14 HIV DNA  ≥ 45 copies/10 cells was associated with reduced volumes of the nucleus accumbens (P=0.021), brainstem (P=0.033) and total gray matter (P=0.045) independently of age, CD4 cell count and intracranial volume.

CONCLUSION

HIV DNA burden in CD14 monocytes is directly linked to brain volumetric loss. Our findings implicate peripheral viral reservoirs in HIV-associated brain atrophy and support their involvement in the neuropathogenesis of HAND, underscoring the need for therapies that target these cells.

Recent developments in the search for a cure for HIV-1 infection: targeting the latent reservoir for HIV-1

HIV-1 infection can now be readily controlled with combination antiretroviral therapy. However, the virus persists indefinitely in a stable latent reservoir in resting CD4(+) T cells. This reservoir generally prevents cure of the infection with combination antiretroviral therapy alone. However, several recent cases of potential HIV-1 cure have generated renewed optimism. Here we review these cases and consider new developments in our understanding of the latent reservoir. In addition, we consider clinical aspects of curative strategies to provide a more realistic picture of what a generally applicable cure for HIV-1 infection is likely to entail.

Use of collateral sensitivity networks to design drug cycling protocols that avoid resistance development

New drug deployment strategies are imperative to address the problem of drug resistance, which is limiting the management of infectious diseases and cancers. We evolved resistance in Escherichia coli toward 23 drugs used clinically for treating bacterial infections and mapped the resulting collateral sensitivity and resistance profiles, revealing a complex collateral sensitivity network. On the basis of these data, we propose a new treatment framework--collateral sensitivity cycling--in which drugs with compatible collateral sensitivity profiles are used sequentially to treat infection and select against drug resistance development. We identified hundreds of such drug sets and demonstrated that the antibiotics gentamicin and cefuroxime can be deployed cyclically such that the treatment regimen selected against resistance to either drug. We then validated our findings with related bacterial pathogens. These results provide proof of principle for collateral sensitivity cycling as a sustainable treatment paradigm that may be generally applicable to infectious diseases and cancer.

Turning ecology and evolution against cancer

The fight against cancer has drawn researchers from a wide variety of disciplines, ranging from molecular biology to physics, but the perspective of an ecological theorist has been mostly overlooked. By thinking about the cells that make up a tumour as an endangered species, cancer vulnerabilities become more apparent. Studies in conservation biology and microbial experiments indicate that extinction is a complex phenomenon, which is often driven by the interaction of ecological and evolutionary processes. Recent advances in cancer research have shown that tumours, like species striving for survival, harbour intricate population dynamics, which suggests the possibility to exploit the ecology of tumours for treatment.

Cytomegalovirus replication in semen is associated with higher levels of proviral HIV DNA and CD4+ T cell activation during antiretroviral treatment

Asymptomatic cytomegalovirus (CMV) replication occurs frequently in the genital tract in untreated HIV-infected men and is associated with increased immune activation and HIV disease progression. To determine the connections between CMV-associated immune activation and the size of the viral reservoir, we evaluated the interactions between (i) asymptomatic seminal CMV replication, (ii) levels of T cell activation and proliferation in blood, and (iii) the size and transcriptional activity of the HIV DNA reservoir in blood from 53 HIV-infected men on long-term antiretroviral therapy (ART) with suppressed HIV RNA in blood plasma. We found that asymptomatic CMV shedding in semen was associated with significantly higher levels of proliferating and activated CD4(+) T cells in blood (P < 0.01). Subjects with detectable CMV in semen had approximately five times higher average levels of HIV DNA in blood CD4(+) T cells than subjects with no CMV. There was also a trend for CMV shedders to have increased cellular (multiply spliced) HIV RNA transcription (P = 0.068) compared to participants without CMV, but it is unclear if this transcription pattern is associated with residual HIV replication. In multivariate analysis, the presence of seminal plasma CMV (P = 0.04), detectable 2-long terminal repeat (2-LTR), and lower nadir CD4(+) (P < 0.01) were independent predictors of higher levels of proviral HIV DNA in blood. Interventions aimed at reducing seminal CMV and associated immune activation may be important for HIV curative strategies. Future studies of anti-CMV therapeutics will help to establish causality and determine the mechanisms underlying these described associations. Importance: Almost all individuals infected with HIV are also infected with cytomegalovirus (CMV), and the replication dynamics of the two viruses likely influence each other. This study investigated interactions between asymptomatic CMV replication within the male genital tract, levels of inflammation in blood, and the size of the HIV DNA reservoir in 53 HIV-infected men on long-term antiretroviral therapy (ART) with suppressed HIV RNA in blood plasma. In support of our primary hypothesis, shedding of CMV DNA in semen was associated with increased activation and proliferation of T cells in blood and also significantly higher levels of HIV DNA in blood cells. These results suggest that CMV reactivation might play a role in the maintenance of the HIV DNA reservoir during suppressive ART and that it could be a target of pharmacologic intervention in future studies.

Mean corpuscular volume (MCV) values reflect therapeutic effectiveness in zidovudine-receiving HIV patients

BACKGROUND

An increase of the mean corpuscular volume (MCV) of erythrocytes and alterations in the lipid profiles have been described in HIV-infected patients under combination of anti-retroviral treatment (cART), particularly zidovudine (AZT).

METHODS

In 687 sera from 179 HIV-positive patients, MCV levels were correlated with the clinical outcome or therapeutic effectiveness. The sera were classified into three groups according to AZT treatment; cART with AZT (n = 317), cART without AZT (n = 262), and no anti-retroviral therapy (n = 108).

RESULTS

The MCV and lipid profile values were increased after cART. The AZT-based cART group had higher MCV levels (111.6 ± 7.0 vs. 97.8 ± 7.0 fl, P < 0.001) and a higher incidence of macrocytosis (>99 fl; 95.3% vs. 38.2%, P < 0.001) than the non-AZT-based cART group. The receiver operating characteristic curve analysis showed that the area under the curve was 0.835 and the cut-off of MCV (>102 fl) had a sensitivity of 96.1% and specificity of 66.7% for detecting HIV-RNA (-) sera in AZT-based cART group. In the multivariate regression analysis, HIV-viral load and HDL-cholesterol were the only significant correlates to the MCV values in the AZT-base cART group (P < 0.05).

CONCLUSION

The MCV values could be used as a surrogate marker to monitor the clinical outcome of HIV-infected patients receiving AZT-based cART.

HIV-1 latency: an update of molecular mechanisms and therapeutic strategies

The major obstacle towards HIV-1 eradication is the life-long persistence of the virus in reservoirs of latently infected cells. In these cells the proviral DNA is integrated in the host’s genome but it does not actively replicate, becoming invisible to the host immune system and unaffected by existing antiviral drugs. Rebound of viremia and recovery of systemic infection that follows interruption of therapy, necessitates life-long treatments with problems of compliance, toxicity, and untenable costs, especially in developing countries where the infection hits worst. Extensive research efforts have led to the proposal and preliminary testing of several anti-latency compounds, however, overall, eradication strategies have had, so far, limited clinical success while posing several risks for patients. This review will briefly summarize the more recent advances in the elucidation of mechanisms that regulates the establishment/maintenance of latency and therapeutic strategies currently under evaluation in order to eradicate HIV persistence.

Rapid screening of HIV reverse transcriptase and integrase inhibitors

Although a number of anti HIV drugs have been approved, there are still problems with toxicity and drug resistance. This demonstrates a need to identify new compounds that can inhibit infection by the common drug resistant HIV-1 strains with minimal toxicity. Here we describe an efficient assay that can be used to rapidly determine the cellular cytotoxicity and efficacy of a compound against WT and mutant viral strains. The desired target cell line is seeded in a 96-well plate and, after a 24 hr incubation, serially dilutions of the compounds to be tested are added. No further manipulations are necessary for cellular cytotoxicity assays; for anti HIV assays a predetermined amount of either a WT or drug resistant HIV-1 vector that expresses luciferase is added to the cells. Cytotoxicity is measured by using an ATP dependent luminescence assay and the impact of the compounds on infectivity is measured by determining the amount of luciferase in the presence or the absence of the putative inhibitors. This screening assay takes 4 days to complete and multiple compounds can be screened in parallel. Compounds are screened in triplicate and the data are normalized to the infectivity/ATP levels in absence of target compounds. This technique provides a quick and accurate measurement of the efficacy and toxicity of potential anti HIV compounds.

Mathematical modeling of HIV prevention measures including pre-exposure prophylaxis on HIV incidence in South Korea

Background

Multiple prevention measures have the possibility of impacting HIV incidence in South Korea, including early diagnosis, early treatment, and pre-exposure prophylaxis (PrEP). We investigated how each of these interventions could impact the local HIV epidemic, especially among men who have sex with men (MSM), who have become the major risk group in South Korea. A mathematical model was used to estimate the effects of each these interventions on the HIV epidemic in South Korea over the next 40 years, as compared to the current situation.

Methods

We constructed a mathematical model of HIV infection among MSM in South Korea, dividing the MSM population into seven groups, and simulated the effects of early antiretroviral therapy (ART), early diagnosis, PrEP, and combination interventions on the incidence and prevalence of HIV infection, as compared to the current situation that would be expected without any new prevention measures.

Results

Overall, the model suggested that the most effective prevention measure would be PrEP. Even though PrEP effectiveness could be lessened by increased unsafe sex behavior, PrEP use was still more beneficial than the current situation. In the model, early diagnosis of HIV infection was also effectively decreased HIV incidence. However, early ART did not show considerable effectiveness. As expected, it would be most effective if all interventions (PrEP, early diagnosis and early treatment) were implemented together.

Conclusions

This model suggests that PrEP and early diagnosis could be a very effective way to reduce HIV incidence in South Korea among MSM.

Increases in duration of first highly active antiretroviral therapy over time (1996-2009) and associated factors in the Multicenter AIDS Cohort Study

BACKGROUND

Antiretroviral therapy (ART) regimens changes occur frequently among HIV-infected persons. Duration and type of initial highly active antiretroviral therapy (HAART) and factors associated with regimen switching were evaluated in the Multicenter AIDS Cohort Study.

METHODS

Participants were classified according to the calendar period of HAART initiation: T1 (1996-2001), T2 (2002-2005), and T3 (2006-2009). Kaplan-Meier curves depicted time from HAART initiation to first regimen changes within 5.5 years. Cox proportional hazards regression models were used to examine factors associated with time to switching.

RESULTS

Of 1009 participants, 796 changed regimen within 5.5 years after HAART initiation. The percentage of participants who switched declined from 85% during T1 to 49% in T3. The likelihood of switching in T3 decreased by 50% (P < 0.01) compared with T1 after adjustment for pre-HAART ART use, age, race, and CD4 count. Incomplete HIV suppression decreased over time (P < 0.01) but predicted switching across all time periods. Lower HAART adherence (≤95% of prescribed doses) was predictive of switching only in T1. In T2, central nervous system symptoms predicted switching [relative hazard (RH) = 1.7; P = 0.012]. Older age at HAART initiation was associated with increased switching in T1 (RH = 1.03 per year increase) and decreased switching in T2 (RH = 0.97 per year increase).

CONCLUSIONS

During the first 15 years of the HAART era, initial HAART regimen duration lengthened and regimen discontinuation rates diminished. Both HIV RNA nonsuppression and poor adherence predicted switching before 2001 while side effects that were possibly ART related were more prominent during T2.

Updated US Public Health Service guidelines for the management of occupational exposures to human immunodeficiency virus and recommendations for postexposure prophylaxis

This report updates US Public Health Service recommendations for the management of healthcare personnel (HCP) who experience occupational exposure to blood and/or other body fluids that might contain human immunodeficiency virus (HIV). Although the principles of exposure management remain unchanged, recommended HIV postexposure prophylaxis (PEP) regimens and the duration of HIV follow-up testing for exposed personnel have been updated. This report emphasizes the importance of primary prevention strategies, the prompt reporting and management of occupational exposures, adherence to recommended HIV PEP regimens when indicated for an exposure, expert consultation in management of exposures, follow-up of exposed HCP to improve adherence to PEP, and careful monitoring for adverse events related to treatment, as well as for virologic, immunologic, and serologic signs of infection. To ensure timely postexposure management and administration of HIV PEP, clinicians should consider occupational exposures as urgent medical concerns, and institutions should take steps to ensure that staff are aware of both the importance of and the institutional mechanisms available for reporting and seeking care for such exposures. The following is a summary of recommendations: (1) PEP is recommended when occupational exposures to HIV occur; (2) the HIV status of the exposure source patient should be determined, if possible, to guide need for HIV PEP; (3) PEP medication regimens should be started as soon as possible after occupational exposure to HIV, and they should be continued for a 4-week duration; (4) new recommendation-PEP medication regimens should contain 3 (or more) antiretroviral drugs (listed in Appendix A ) for all occupational exposures to HIV; (5) expert consultation is recommended for any occupational exposures to HIV and at a minimum for situations described in Box 1 ; (6) close follow-up for exposed personnel ( Box 2 ) should be provided that includes counseling, baseline and follow-up HIV testing, and monitoring for drug toxicity; follow-up appointments should begin within 72 hours of an HIV exposure; and (7) new recommendation-if a newer fourth-generation combination HIV p24 antigen-HIV antibody test is utilized for follow-up HIV testing of exposed HCP, HIV testing may be concluded 4 months after exposure ( Box 2 ); if a newer testing platform is not available, follow-up HIV testing is typically concluded 6 months after an HIV exposure.

Durable HIV RNA resuppression after virologic failure while remaining on a first-line regimen: a cohort study

Adherence interventions are a recommended strategy to salvage failing antiretroviral therapy without regimen change. We assessed the durability of resuppression when using this approach. Of 300 patients who resuppressed on the same regimen (41% of all those with virologic failure), 148 (45%) remained suppressed during follow-up for a median of 2.4 years (interquartile range [IQR]: 1.1, 4.0). Resuppression can be durable following viraemia without a switch in antiretroviral therapy regimen.

Cellular HIV type 1 DNA levels are equivalent among drug-sensitive and drug-resistant strains in newly diagnosed and antiretroviral naive patients

The emergence of resistance against current antiretroviral drugs to human immunodeficiency virus type 1 (HIV-1) is an increasingly important concern to the continuous success of antiretroviral therapy to HIV-1-infected patients. In the past decade, a number of studies reported that the prevalence of transmitted drug resistance among newly diagnosed patients has reached an overall 9% prevalence worldwide. Also, a number of studies using longitudinal HIV-1 patient study cohorts demonstrated that the cellular HIV-1 DNA level in peripheral blood mononuclear cells (PBMCs) has a prognostic value for the progression of HIV-1 disease independently of plasma HIV-1 RNA load and CD4 count. Using a previously established molecular-beacon-based real-time PCR methodology, cellular HIV-1 DNA levels were quantified in newly diagnosed and antiretroviral-naive patients in Northern Greece recruited between 2009 and 2010 using a predefined enrolling strategy, in an effort to investigate whether there is any relationship between cellular HIV-1 DNA levels and HIV-1 transmitted drug resistance. As part of the same study, DNA sequences encoding the env (C2-C5 region of gp120) were also amplified from PBMC-extracted DNA in order to determine the genotypic coreceptor tropism and genetic subtype. Cellular HIV-1 DNA levels had a median of 3.309 log10 HIV-1 copies per 10(6) PBMCs and demonstrated no correlation between cellular HIV-1 DNA levels and HIV-1 transmitted drug resistance. An absence of association between cellular HIV-1 DNA levels with plasma viral HIV-1 RNA load and CD4 levels was also found reconfirming the previously published study. Genotypic analysis of coreceptor tropism indicated that 96% of samples, independently of the presence or not of genotypic drug resistance, were CCR5-tropic. Overall, the findings reconfirmed the previously proposed proposition that transmitted drug resistance does not have an impact on disease progression in HIV-1-infected individuals. Also, CCR5 coreceptor tropism dominance suggests that both drug-resistant and drug-sensitive strains behave similarly in early infection in newly diagnosed patients.

Highly active antiretroviral therapies are effective against HIV-1 cell-to-cell transmission

HIV-1 cell-to-cell transmission allows for 2-3 orders of magnitude more efficient viral spread than cell-free dissemination. The high local multiplicity of infection (MOI) observed at cell-cell contact sites may lower the efficacy of antiretroviral therapies (ART). Here we test the efficacy of commonly used antiretroviral inhibitors against cell-to-cell and cell-free HIV-1 transmission. We demonstrate that, while some nucleoside-analog reverse transcriptase inhibitors (NRTI) are less effective against HIV-1 cell-to-cell transmission, most non-nucleoside-analog reverse transcriptase inhibitors (NNRTI), entry inhibitors and protease inhibitors remain highly effective. Moreover, poor NRTIs become highly effective when applied in combinations explaining the effectiveness of ART in clinical settings. Investigating the underlying mechanism, we observe a strict correlation between the ability of individual drugs and combinations of drugs to interfere with HIV-1 cell-to-cell transmission, and their effectiveness against high viral MOIs. Our results suggest that the ability to suppress high viral MOI is a feature of effective ART regimens and this parameter should be considered when designing novel antiviral therapies.

The next generation of HIV/AIDS drugs: novel and developmental antiHIV drugs and targets

There are presently 42 million people worldwide living with HIV/AIDS, the majority of which have limited access to antiretrovirals. Even if worldwide penetration was possible, our current chemotherapeutic strategies still suffer from issues of cost, patient compliance, deleterious acute and chronic side effects, emerging single and multidrug resistance, and generalized treatment and economic issues. Even our best antiretroviral therapeutic strategy, highly active antiretroviral therapy (HAART), falls short of completely suppressing HIV replication. Therefore, expansion of current therapeutic options by discovering new antiretrovirals and targets will be critical in the coming years. This review addresses the current status of reverse transcriptase and protease inhibitor development, and summarizes the progress in emerging classes of HIV inhibitors, including entry (T-20, T-1249), coreceptor (SCH-C, SCH-D), integrase (beta-Diketos) and p7 nucleocapsid Zn finger inhibitors (thioesters and PATEs). In addition, the processes of virus entry, PIC transport to the nucleus, HIV interaction with nuclear pores, Tat function, Rev function and virus budding (Tsg101 and ubiquitination) are examined, and proof of concept inhibitors and potential antiviral targets discussed.

HIV/AIDS pathogenesis and treatment options focusing on the viral entry inhibitors

The advent of highly active antiretroviral therapy (HAART) has revolutionized the treatment of HIV. A wide variety of antiretroviral agents are now available, allowing patients and physicians a choice of effective therapy. However, drug resistance and toxicities are emerging as major treatment challenges in the HAART era. The development of agents within existing and novel antiretroviral classes remains paramount in order to preserve the reduced morbidity and mortality we have come to expect from HAART use. This article details the development of the HIV epidemic, reviewing current and future treatment strategies, and concentrating upon the viral entry inhibitors.

HIV-1 eradication strategies: design and assessment

PURPOSE OF REVIEW

Recent developments have generated renewed interest in the possibility of curing HIV-1 infection. This review describes some of the practical challenges that will need to be overcome if curative strategies are to be successful.

RECENT FINDINGS

The latent reservoir for HIV-1 in resting memory CD4 T cells is the major barrier to curing the infection. The most widely discussed approach to curing the infection involves finding agents that reverse latency in resting CD4 T cells, with the assumption that the cells will then die from viral cytopathic effects or be lysed by host cytolytic T lymphocytes (CTLs). A major challenge is the development of in-vitro models that can be used to explore mechanisms and identify latency-reversing agents (LRAs). Although several models have been developed, including primary cell models, none of them may fully capture the quiescent state of the cells that harbour latent HIV-1 in vivo. An additional problem is that LRAs that do not cause T-cell activation may not lead to the death of infected cells. Finally, measuring the effects of LRAs in vivo is complicated by the lack of correlation between different assays for the latent reservoir.

SUMMARY

Progress on these practical issues is essential to finding a cure.

From GRID to gridlock: the relationship between scientific biomedical breakthroughs and HIV/AIDS policy in the US Congress

INTRODUCTION

From the travel ban on people living with HIV (PLHIV) to resistance to needle exchange programmes, there are many examples where policy responses to HIV/AIDS in the United States seem divorced from behavioural, public health and sociological evidence. At its root, however, the unknowns about HIV/AIDS lie at biomedical science, and scientific researchers have made tremendous progress over the past 30 years of the epidemic by using antiretroviral therapy to increase the life expectancy of PLHIV almost to the same level as non-infected individuals; but a relationship between biomedical science discoveries and congressional responses to HIV/AIDS has not been studied. Using quantitative approaches, we directly examine the hypothesis that progress in HIV/AIDS biomedical science discoveries would have a correlative relationship with congressional response to HIV/AIDS from 1981 to 2010.

METHODS

This study used original data on every bill introduced, hearing held and law passed by the US Congress relating to HIV/AIDS over 30 years (1981-2010). We combined congressional data with the most cited and impactful biomedical research scientific publications over the same time period as a metric of biomedical science breakthroughs. Correlations between congressional policy and biomedical research were then analyzed at the aggregate and individual levels.

RESULTS

Biomedical research advancements helped shape both the level and content of bill sponsorship on HIV/AIDS, but they had no effect on other stages of the legislative process. Examination of the content of bills and biomedical research indicated that science helped transform HIV/AIDS bill sponsorship from a niche concern of liberal Democrats to a bipartisan coalition when Republicans became the majority party. The trade-off for that expansion has been an emphasis on the global epidemic to the detriment of domestic policies and programmes.

CONCLUSIONS

Breakthroughs in biomedical science did associate with the number and types of HIV/AIDS bills introduced in Congress, but that relationship did not extend to the passage of laws or to hearings. When science matters, it cannot be separated from political considerations. An important implication of our work has been the depoliticizing role that science can play. Scientific breakthroughs helped to transform HIV/AIDS policy from a niche of liberal Democrats into bipartisan support for the global fight against the disease.

A novel cell-based high-throughput screen for inhibitors of HIV-1 gene expression and budding identifies the cardiac glycosides

OBJECTIVES

Highly active antiretroviral therapy (HAART) is the mainstay of treatment for HIV-1 infection. While current HAART regimens have been extremely effective, issues of associated toxicity, cost and resistance remain and there is a need for novel antiretroviral compounds to complement the existing therapy. We sought to develop a novel high-throughput method for identifying compounds that block later steps in the life cycle not targeted by current therapy.

METHODS

We designed a high-throughput screen to identify inhibitors of post-integration steps in the HIV-1 life cycle. The screening method was applied to a library of compounds that included numerous FDA-approved small molecules.

RESULTS

Among the small molecules that inhibited late stages in HIV-1 replication were members of the cardiac glycoside family. We demonstrate that cardiac glycosides potently inhibit HIV-1 gene expression, thereby reducing the production of infectious HIV-1. We demonstrate that this inhibition is dependent upon the human Na(+)/K(+)-ATPase, but independent of cardiac glycoside-induced increases in intracellular Ca(2+).

CONCLUSIONS

We have validated a novel high-throughput screen to identify small molecule inhibitors of HIV-1 gene expression, virion assembly and budding. Using this screen, we have demonstrated that a number of FDA-approved compounds developed for other purposes potently inhibit HIV-1 replication, including the cardiac glycosides. Our work indicates that the entire cardiac glycoside family of drugs shows potential for antiretroviral drug development.

Mental health of HIV-infected patients: A severe, but Overlooked Problem

HIV-infected patients are known to have severe psychosocial problems; however, clinicians tend to overlook these psychosocial issues. Song et al. identified depression and anxiety as the most common mental illnesses among HIV-infected patients. Psychosocial issues are important factors and are associated with poor adherence, which leads to treatment failure and resistance. Clinicians who tend to HIV patients should be attentive to the patients' psychosocial problems and regularly conduct screening for depressive disorders. Mental health must be addressed to improve the quality of life of patients with HIV/AIDS.

Health status, sexual and drug risk, and psychosocial factors relevant to postrelease planning for HIV+ prisoners

The prevalence of HIV infection among male prison inmates is significantly higher than in the U.S. population. Adequate planning to ensure continued medication adherence and continuity of care after release is important for this population. This study describes the prerelease characteristics of 162 incarcerated HIV-positive men (40 from jails and 122 from prisons). The results include a demographic description of the sample and the participants' sexual risk behaviors, substance use, health status and HIV medication adherence, health care utilization, mental health, and family and social support. The results highlight a potentially high level of need for services and low levels of support and social connectedness. Postrelease planning should include support for improving HIV medication adherence as well as reducing both sexual and injection drug-related transmission risk for these individuals.

HIV-1 transmission during early antiretroviral therapy: evaluation of two HIV-1 transmission events in the HPTN 052 prevention study

In the HPTN 052 study, transmission between HIV-discordant couples was reduced by 96% when the HIV-infected partner received suppressive antiretroviral therapy (ART). We examined two transmission events where the newly infected partner was diagnosed after the HIV-infected partner (index) initiated therapy. We evaluated the sequence complexity of the viral populations and antibody reactivity in the newly infected partner to estimate the dates of transmission to the newly infected partners. In both cases, transmission most likely occurred significantly before HIV-1 diagnosis of the newly infected partner, and either just before the initiation of therapy or before viral replication was adequately suppressed by therapy of the index. This study further strengthens the conclusion about the efficacy of blocking transmission by treating the infected partner of discordant couples. However, this study does not rule out the potential for HIV-1 transmission to occur shortly after initiation of ART, and this should be recognized when antiretroviral therapy is used for HIV-1 prevention.

Recent trends in HIV-1 drug resistance

Once considered an inevitable consequence of HIV treatment, drug resistance is declining. This decline supports the hypothesis that antiretroviral therapy can arrest replication and prevent the evolution of resistance. Further support comes from excellent clinical outcomes, the failure of treatment intensification to reduce residual viremia, the lack of viral evolution in patients on optimal therapy, pharmacodynamics studies explaining the extraordinarily high antiviral activity of modern regimens, and recent reports of potential cures. Evidence supporting ongoing replication includes higher rates of certain complications in treated patients and an increase in circular forms of the viral genome after intensification with integrase inhibitors. Recent studies also provide an explanation for the observation that some patients fail protease-inhibitor based regimens without evidence for resistance.

Anti-HIV designer T cells progressively eradicate a latently infected cell line by sequentially inducing HIV reactivation then killing the newly gp120-positive cells

The current antiretroviral therapy (ART) can effectively reduce plasma HIV loads to undetectable levels, but cannot eliminate latently infected resting memory CD4 T cells that persist for the lifetime of infected patients. Therefore, designing new therapeutic approaches to eliminate these latently infected cells or the cells that produce HIV upon reactivation from latency is a priority in the ART era in order to progress to a cure of HIV. Here, we show that "designer" T cells expressing chimeric antigen receptor (CAR), CD4-CD28-CD3ζ, can target and kill HIV Env-expressing cells. Further, they secrete effector cytokines upon contact with HIV Env+ target cells that can reactivate latent HIV in a cell line model, thereby exposing those cells to recognition and killing by anti-HIV CAR+ T cells. Taken to the limit, this process could form the basis for an eventual functional or sterilizing cure for HIV in patients.

Evolving uses of oral reverse transcriptase inhibitors in the HIV-1 epidemic: from treatment to prevention

The HIV epidemic continues unabated, with no highly effective vaccine and no cure. Each new infection has significant economic, social and human costs and prevention efforts are now as great a priority as global antiretroviral therapy (ART) scale up. Reverse transcriptase inhibitors, the first licensed class of ART, have been at the forefront of treatment and prevention of mother to child transmission over the past two decades. Now, their use in adult prevention is being extensively investigated. We describe two approaches: treatment as prevention (TasP) - the use of combination ART (2NRTI and 1NNRTI) following HIV diagnosis to limit transmission and pre-exposure prophylaxis (PrEP) –the use of single or dual oral agents prior to sexual exposure. Prevention of mother-to-child transmission using NRTI has been highly successful, though does not involve sustained use of NRTI to limit transmission. Despite theoretical and preliminary support for TasP and PrEP, data thus far indicate that adherence, retention in care and late diagnosis are the major barriers to their successful, sustained implementation. Future advances in drug technologies will be needed to overcome the issue of drug adherence, through development of drugs that involve both less frequent dosing as well as reduced toxicity, possibly through specific targeting of infected cells.

Endothelial cell stimulation overcomes restriction and promotes productive and latent HIV-1 infection of resting CD4+ T cells

Highly active antiretroviral therapy (HAART) is able to suppress human immunodeficiency virus type 1 (HIV-1) to undetectable levels in the majority of patients, but eradication has not been achieved because latent viral reservoirs persist, particularly in resting CD4(+) T lymphocytes. It is generally understood that HIV-1 does not efficiently infect resting CD4(+) T cells, and latent infection in those cells may arise when infected CD4(+) T lymphoblasts return to resting state. In this study, we found that stimulation by endothelial cells can render resting CD4(+) T cells permissible for direct HIV infection, including both productive and latent infection. These stimulated T cells remain largely phenotypically unactivated and show a lower death rate than activated T cells, which promotes the survival of infected cells. The stimulation by endothelial cells does not involve interleukin 7 (IL-7), IL-15, CCL19, or CCL21. Endothelial cells line the lymphatic vessels in the lymphoid tissues and have frequent interactions with T cells in vivo. Our study proposes a new mechanism for infection of resting CD4(+) T cells in vivo and a new mechanism for latent infection in resting CD4(+) T cells.

Differential penetration of raltegravir throughout gastrointestinal tissue: implications for eradication and cure

OBJECTIVE

To investigate the concentration of the integrase strand inhibitor raltegravir (RAL) throughout gastrointestinal (GI) tissue, especially gut-associated lymphoid tissue (GALT), as an adjunct to current prevention and cure strategies.

DESIGN

Open-label pharmacokinetic (PK) study.

METHODS

HIV-negative men received RAL 400 mg twice daily for 7 days. Seven blood plasma specimens were collected over 12-h intervals; timed tissue specimens from terminal ileum, splenic flexure, and rectum were also obtained by colonoscopy following the first dose and on day 7 [multiple dose (MD)]. RAL concentrations were measured by validated LC-MS assay with 1 ng/ml lower limit of detection. Data were analyzed by noncompartmental methods (WinNonlin 6). Tissue exposures are reported as composite medians and tissue density of 1.04 g/ml is assumed for comparisons.

RESULTS

Fourteen men completed evaluations. Median (range) age was 24 (19-49) years and BMI 25 (19-31) kg/m². After the first dose, area under the time-concentration curve (AUC)(0-12h) was highest in the terminal ileum (594 μg*h/ml). Exposures were 160, 68 and 39-fold greater than blood plasma at the terminal ileum, splenic flexure and rectum, respectively. After multiple doses, exposure was highest at the splenic flexure (2240 μg*h/ml); exposure at the terminal ileum and rectum were equivalent (both 788 μg*h/ml). Following multiple doses, exposures were 160 to 650-fold greater than blood plasma throughout the colon.

CONCLUSION

RAL rapidly disseminates into GI tissue and concentrations remain significantly higher than blood plasma. RAL exposure in GI tissue remains higher than any antiretroviral investigated to date. These data suggest that RAL should result in full suppression of viral replication in GI tissue and GALT.